The present invention relates to mechanical curtains and more particularly to vertically movable partitions for use within buildings, example to cordon off areas, as required, to prevent public access or for crowd control.
Security partitions in the form of security gates are well known and may take the form of horizontally sliding bar systems, for example to close off open fronts of shops in shopping centers or to be moved across entrance ways to shops on streets. These types of movable security gates usually require storage space beside the area being protected, to accommodate the gate components when not in use. Conversely, existing xe2x80x9croll-upxe2x80x9d security gates are stored in ceiling space when not in use. This type of gate is severely limited in width and height as the roller can only be supported at its ends and cannot deflect under the load of the gate.
U.S. Pat. No. 5,062,464 of Miles Peterson, issued Nov. 5, 1991 describes and illustrates a wall partition, which uses a pantograph type of construction to provide a rigid wall section, which is vertically collapsible and movable to a storage position. Movable wall partition systems have similar problems of storage and structural support requirements and the Peterson vertically movable wall partition avoids those problems by providing ceiling storage for the wall partitions and a single permanent location for all of the panels so that the loads imposed on the building support structure do not vary because of lateral movement of the panels. Further, this design of the wall system allows the partition to be of any width or height as it is lifted and supported at multiple points across its width. This is made possible as the partition is folded up rather than rolled up.
The pantograph structure as suggested by the Peterson construction is similar to that for instance found in baby gates in which a series of elongated members are pivotally linked together in spaced fashion to provide a series of similar diamonds along the length of the gate. In a single (as opposed to multiple) pantograph construction, a pair of members of similar size are pivotally linked at their midpoints. One pair of their ends are pivotally linked to the ends of a further corresponding pair of members of similar length similarly pivoted at their midpoint, and so on. The midpoints of the members are longitudinally aligned and form opposed longitudinal apexes of diamond shapes; the other opposed corners of these diamonds are formed by the pivotally secured ends of adjacent pairs of intersecting members, and are the lateral apexes. The pantograph structure expands and contracts longitudinally. The pantograph structure in such applications is useful because it causes forces applied longitudinally, in the direction of expansion and contraction of the pantograph, to be transmitted evenly throughout all of the members of the pantograph structure. As well, all of the apexes of the diamonds formed by the points of intersection of the members, as the structure is contracted, will arrive at their final, fully contracted position at the same time, meaning that the longitudinal apexes of the diamonds at one end of the pantograph structure, which are moving towards the other end during contraction, will move at a much greater speed than the apexes of the diamonds at the other end.
It is an object of the present invention to provide a mechanical curtain, which is based on these pantograph principles.
In accordance with the present invention there is provided a mechanical curtain, upwardly movable into open position and downwardly movable into closed position. The curtain comprises a plurality of similarly constructed trains of elongated members, the members of each train arranged to form a single pantograph forming longitudinally aligned rows of diamonds. The trains are spaced laterally to lie within a curtain plane and are oriented so that the pantographs operate in a plane at a 90xc2x0 angle to that curtain plane. A plurality of bars are secured in parallel spaced fashion to corresponding members of adjacent trains, perpendicular thereto. Means are provided to raise and lower the trains at a similar rate, the pantographs being contracted when the curtain is in open position and being elongated when the curtain is in closed position.
In one embodiment of the present invention, particularly applicable for use as a security gate, the curtain is further provided with locking means to secure the curtain in closed position against unwanted opening.
The curtain according to the present invention has many advantages. When used as a security gate, because its components move vertically rather than horizontally, storage space is not required to the side of the entrance way or other area within which the curtain operates, since the curtain folds and stores above the passageway or area in question. Furthermore, because the curtain does not move horizontally, the loads imposed on the support structure are constant. Also, the height and width restrictions present with conventional roll-up security gates are avoided since the curtain of the present invention may be lifted and supported at multiple points across its width.